The known techniques for preparing 1-alkene containing copolymers yield products which have a wide molecular weight diversity and an extreme compositional heterogeneity. While the copolymers formed may display some beneficial properties, the overall effect of using a given amount of the polymer will be diminished by that part of the product having a molecular weight or composition which possesses detrimental or non-useful qualtities. Thus, in order to produce a polymer in which the good qualities are concentrated so that less of the polymer need be used to accomplish a desired effect, it would be desirable to employ a polymerization technique which would allow for such control of polymer molecular weight and composition so that most of the polymeric material produced would have the beneficial qualities sought.
The prior art discloses a series of amide-containing copolymers which are disclosed as useful as additives to oil, to wit, Bondi 2,800,452 (filed July 1954), and Newey 2,912,416 (also filed July 1954). They do not, however, teach or suggest the presently disclosed 1-alkenesalkyl acrylates higher alkyl acrylate oligomers, which have superior sludge dispersant properties.
The '416 patent recites an amide-containing copolymer based on components which cannot produce the presently taught oligomers.
Similarly, the '452 patent does not include the higher alkyl acrylate components of the type contemplated for use in the presently taught oligomers; rather, it intended to exclude long chain esters, which we have discovered contribute significantly to the here-desired oil-solubility and/or dispersancy of the resulting oligomer.
Indeed, it can fairly be said that the cited patents actually lead away from using higher alkyl acrylates, in view of their statements that such components are undesirably hydrolytically unstable.